Hello Linda, welcome to the forum
You hear your Audio CDs OK, but get no sound from movies (I'm guessing you're talking about movie DVDs and not movie files such as .avi etc).
If you are talking about movie files, does the problem occur on all movie files, or just a select few? If so, the files themselves may be the problem.
Lastly, what player are you using to view your movies? I personally use the free VLC - you might like to give that a go, and see if it makes a difference.